Azo dyestuffs and process of preparing same



Patented May 19, 1942 AZO DYESTUFFS AND PROCESS OF PREPARING SAME Fritz Straub-, K-aiser-Augst, near Basel, Peter Pieth and Walter Anderau, Basel, and Walter Hanhart, Riehen,

Switzerland, assignors to Society of Chemical Industry in Basle, Basel,

Switzerland N Drawing. Application August 8, 1939, Serial No. 289,038. In Switzerland August 16, 1938 17 Claims.

characteristic of B-hydroxyquinoline; if desired the dyestuff thus obtained is treated with an agent yielding metal.

For making such dyestuffs a first component may be diazotized and coupled with a middle component, the azo-dyestuff thus obtained being further diazotized, coupled once more with a middle component and then after further diazotization coupled with an end component.

In this procedure there is preferably used as the first component a diazo compound of the benzene or naphthalene series; such are for. example sulfonic acids of aniline or a homologue or substitution product thereof, .aminocarboxylic acids, for instance anthranilic acid or aminosalicylic acid, land 2-aminonaphthalene-sulfonic acids, for instance l-aminonaphthalenelor 5-sulfonic acid, 2-aminonaphthalene-4i8 or 6:8-disulfonic acid, O-esters of 1:8-aminonaphthol-sulfonic acids or the like. As middle components there may be used aniline (in the form of the so-called aniline-wmethane-sulf0nic acid), meta-toluidine, cresidine, l-amino-2z5-dialkoxybenzene, 5-amino-8-hydroxyquinoline, l-aminonaphthalene, l-aminonaphthalene-B- or 7-sulfonic acid, l-amino-2-alkoXy-naphthalenes such as l-amino-Z-methoxyand Z-ethOXy-naphthalene and its 6- or '7-sulfonic acid or the like. As end components there are used those binuclear compounds which .have the atomic grouping named above characteristic of S-hydroxy-quinoline, for example 8-hydroxyquinoline itself or a substitution product thereof, for instance an 8 hydroxyquinoline containing as a substituent halogen or a sulfonic acid group. There may also be used as first components 8-hydroxyquinolines containing as substituents amino-groups and if desired further groups. It is not however necessary to use the 8-hydroxyquinoline as third component. If the trisazo-dyestufi contains groups capable of being diazotized or groups which are capable of conversion into diazotizable groups which, if desired after conversion into amino groups, may be diazotized, such a diazo-trisazo-compound may be coupled with the compound containing the S-hydroxyquinoline grouping. This is the case for example when there has been used as third component 2-amino-5- or B-hydroxynaphthalene-Y- or G-sulfonic acid or as the first component para-nitraniline, para-- mtraniline-ortho-sulfonic acid, acetyl-paraphenylenediamine or l-aminol-acetyl-aminonaphthalene-G-sulfonic acid.

The dyestufis in question may also be made by coupling a tetrazo-compound, for example 4 tetrazodi-phenyl, 3 3-dimethyl-4 :4-tetrazodiphenyl, 3-: 3 -dimethoXy-4 :4 -tetrazodiphenyl or the like, substituted'in 3- 'or 3"-position first with l or 2 mol of the suitable middle component, for example l-naphthylamihe-G- or 7-sulfonic acid or 2-amino-5- or 8-hydroxynaphthalene-7- or 6- sulfonicacid and then coupling the dyestuff thus obtained after diazotization or tetrazotization with 2 mole of an azo-component, at least one mol of a hydroxyquinoline compound as defined above being used. In the manufacture of dyestuiis of this type it is obvious that the sequence of the operations may be varied. Advantageously tetrazo compounds as described above maybe coupled on the one-hand with coupling components containing groups capable of forming complex metal compounds, for instance an arylortho-hydroxy-carboxylic acid such as salicylic acid and on the other hand with middle components, as described.

Among the many other possibilities for making dyestuffs of the kind in question there may be mentioned the use of derivatives of Z-amino- 5-hydroxynaphtha1ene-7-sulfonic acid preferably in the form of the corresponding dinaphthylamine compound or its N-acyl derivative, for instance the urea of 2-amino-5-hydroxynaphthalene-7-sulfonic acid, as the azo-component. Such compounds are for instance coupled with a diazo compound containing the radical of the hydroxyquinoline. In making urea derivatives the linking of the two amines with phosgene. to form the urea may occur after the coupling. Quite generally it is also possible to introduce the hydroxyquinoline radical into the new dyestuff by means of a reaction other than a coupling reaction. Such reactions. are in addition to the stated phosgenizing quite generally acylation, condensation with compounds. containing activehah ogen atoms, for. example with triazine derivatives, reduction. of nitro-groups to azoor, azoxygroups, for example by the. processdescribed in U. S. A. patent applications Serial. No. 148,414, filed June 15, 1937, and Serial No. 148,410"; filed preferably 4*:4-tetrazodiphenyl June 15, 1937 (corresponding to British Patents Nos. 491,551 and 497,350). In many cases it is of advantage to use components which impart enhanced afiinity for vegetable fiber to the dyestuff, for instance 4:4-diaminodiphenyl derivatives, diaminostilbenedisulfonic acid, dehydrothiotoluidine, derivatives of 2-amino-5-hydroxynaphthalene sulfonic acid, components of highly condensed ring systems, for example carbazole derivatives, components containing NHfi-NH or --NHCO-groups, like 4::4-diaminodiphenyl ureas or 4-benzoylaniline.

The dyestuffs obtained owing to the presence of the hydroxyquinoline radical are capable of being metallized. This property can be enhanced when components are used which comprise lakeforming groups, that is to say groups which lead to favorable orientations of OH, NH2, NH and COOH among themselves or in combination with the azo-groups. Such orientations are for example ortho-ortho-oxyazo-, ortho-oxy-orthoaminoazo-, ortho-oxy-ortho-carboxyazo and salicylic acid groups. i

The orientations may be obtained by selecting diazoand azo-components which produce these orientations or by converting in the finished azo-dyestuiT halogen atoms, also O-alkyl-, O- acyl-groups or C-OO-alkyl groups into OH- or COOH-groups respectively, a change which may be carried out during the metallizing if desired.

Dyestufis obtainable by this invention may be used for dyeing various materials, for example animal fibers like. wool, silk or leather and particularly vegetable fibers, like cotton and linen or fibers from regenerated cellulose like artificial silk and staple fiber; they may also be used as pigment dyestufis. Cellulosic fibers may be dyed by the dyestuffs by the direct dyeing processes, for example in a bath containingsodium sulfate and if desired sodium carbonate. By after-treating the dyeings with agents yielding metal in a fresh bath or in the bath that hasbeen used for dyeing, dyeings of excellent properties of fast ness may be obtained. As metal yielding agents metal salts may be used in known manner, especially copper salts, for instance copper sulfate. With advantage the processes described in U. S. A. Patent No. 2,148,659 and U. S. A. patent application Serial No. 116,038, filed December 15, 1936, (corresponding to British Patent No. 468,-

or pyridine and in an open vessel or under pressure; as metal yielding agents various metal compounds are available, for example salts of iron, chromium, nickel, cobalt and especially copper.

The metalliferous azo-dyestuffs thus obtainable may be used for dyeing the various materials named above, very fast dyeings of various tints being obtained. If these complex metal compounds are sparingly soluble to insoluble, the

process of U. S. A. Patent No. 2,092,429 may be used.

The following examples illustrate the invention, the parts being by weight:

EmampZeI 15.3 parts of 1-hydroxy-2-carboxy-4-aminobenzene are dissolved in 500 parts of water containing 25 parts of hydrochloric acid and are converted into the diazo compound by addition of 7 parts of sodium nitrite at 15 C. Into this mixture there are run 22.3 parts of l-aminonaphthalene-7-sulfonic acid in the form of its ammonium salt dissolved in 200 parts of water. Within about 10 hours the amino-azo-compound separates in the form of a blackish precipitate and is filtered. It is now dissolved in 500 parts of water and 20. parts of caustic soda solution of B. and converted into the diazonium compound by means of parts of concentrated hydrochloric acid and 7 parts of sodium nitrite. There is then added another 22.3 parts of l-naphthylamine-I-sulfonic acid or a corresponding quantity of 1-aminonaphthalene-'6-sulfonic acid or of the commercial mixture of the two acids in the form of alkali salts dissolved in 200 parts of water. Any excess of free mineral acid which may be present is buffered by means of sodium acetate. After 10 hours coupling is complete. The blackish dyestufi is filtered and dissolved in 500 parts of water and 20 parts of caustic soda of 40 B. To this solution 7 parts of sodium nitrite and suincient ice to produce a temperature of 46 C. are added. 50 parts of hydrochloric acid are then added and stirring is continued for some time until diazotization is completed. This diazonium compound is added to a solution of 14.5 parts 'of 8-hydroxyquinoline in 500 parts of water which contain 20 parts of caustic soda solution of 40 B. and 30 parts of anhydrous sodium carbonate. The blue trisazo-dyestufi is quickly formed as a black precipitate. It is filtered and dried. It is a black powder which corresponds to the formula SOsH 362) may be used and especially such metallizing agents may be used as are stable to alkalis, for instance agents made by the action of hydroxycarboxylic acids on copper salts, the use of which is possible for example in the presence of alkalicarbonate or caustic alkali.

Especially valuable products are obtained in many cases if a metal yielding agent is caused to act on an azo-dyestuff obtainable by the invention. This treatment which may also follow in the dye-bath may occur in known'manner in an acid, neutral or alkaline medium with or without a suitable addition, for instance a salt like common salt, a free organic acid or a salt thereof and in presence or absence of a suitable dispersing agent or solvent, for instance alcohol, glycerine Example 2 18.2 parts of 4:4'-diaminodiphenyl are tetrazotized in the usual manner and the tetrazo-compound is coupled in alkaline solution with 13.8 parts of 1-hydroxybenzene-2-carboxylic acid. When the tetrazo-compound has disappeared 'there is added a solution neutralized with sodium carbonate of 22.3 parts of l-aminonaphthalene- The purifieddyestufi is again indirectly tetra.- fi-sulfonic acid and the mass is acidified. with zotizedi as described above. There is then addedv acetic acid of 50 per cent strength. The coupling; a solution of 30 parts: of ii-hydroxyquinoline inv is conducted at. first for 6 hours below 20 C. and hydrochloric acid solution and the mass is renfinally for 12. hours while stirring at 25-30 C. dere'd alkaline by addition. of sodium carbonate The disazo-dyestufi' is filtered and purified by re-: solution. of 20 per cent strength. Coupling is precipitation from water. continued for 20-60. hours at 10-15 C. The new This disazo-dyestufi is then dissolved 2000. dyestufiis filtered, if desired purified, and dried. parts of water containing 10.6. parts of. anhy- I-t correspondsto the formula N=N N=L N=N-Q-ON=N OOH 000132 \N s oln S OsH drous sodium carbonate, 6.9 parts of sodium ni It is a g-rey bl'ack powder soluble in water, in

trite dissolved in 25 parts of water are added sodium carbonate solution of 10 per cent.

and the whole is acidified at 5 C. bymeans of 50 strength and in-ca-ustic soda solution of 10' per parts of concentrated hydrochloric acid. The dicent strength to blackish-violet solutions and in azotizing occupies about 12 hours and coupling concentrated sulfuric acid to a black-green so1u-" at 10-15 C. with 16 parts of S-hydroxyquinoline tion. The new dyestufi dyes cotton grey tints in a solution alkaline with sodium carbonate folwhich become very fast when after-treated with lows. At the end of this coupling the temperacopper salt. a

ture is raised to 60 C. and the dyestufi is salted Example 4 out and purified by reprecipitation from water. When dry, the new trisazo-dyestufi of the for- 15.4 -parts of 5-nitro-2-amino-l-hydroxybenmula zene are diazotized and coupled in a solution I N I SOaH is a grey-black powder soluble in water to a alkaline with sodium carbonate with 24 parts of brown-orange solution sparingly in sodium'car- 2-amino-5-hydroxynaphthalene-7-sulfonic acid. bonate solution of 10 per cent strength and in When coupling is complete the dyestufi is filcaustic soda solution of 10 per cent strength to a 40 tered, washed with some dilute sodium chloride brown-orange solution and in concentrated sulsolution and then dissolved by the aid of 20 furic acid to a blue solution. It dyes cotton parts of caustic soda solution of 30 per cent brown tints which acquire good fastness to wash-V strength in 1000 parts of luke-warm water.

ing and light when after-treated With a copper After addition of anaqueous solution of 6 parts 0 salt. of sodium nitritethe whole is allowed to run, Example 3 while stirring well, into a mixture of ice and 58 parts Of 4:4-dilamirrodiphe y -3I= "-diparts of hydrochloric acid of 30 per cent carboXylic acid are tetrazotized in known strength. -After the diazo suspension has been ner and coupled in acetic acid solution with 4'7 ti r d for some hours it is coupled in a soluparts of 1-aminonaphthalene-G-sulphonic acid. tion alkaline with sodium carbonate with a sus- When coupling is complete the dyestufl" is 111- pension of 13 parts of 8-hydroxyquinoline. tered and pu fi y reprecipitation from t When coupling is complete some sodium chloride The purified dyestufi paste is dissolved in dilute is added and the dyestuff is filtered. The latter sodium carbonate solution, 13.8 parts of sodium is now treated by the process described in nitrite are added and the mixture is acidified U. S. A. patent application Serial No. 148,414, at 10 C. with hydrochloric acid of 15 per cent filed June 15, 1937, in an alkaline solution with strength. Tetrazotizing is continued for 8-12 dextrose. There is obtained a dyestuff of the hours at 10-15 C. There is then added so much formula concentrated sodium acetate solution that the which dyes cotton a tint that when treated with mineral acid reaction disappears; the solution is copper salt becomes a blue-grey very fastto light then coupled at 15-35" C. with the solution neuand washing.

tralized with sodium carbonate of 4'7 parts of 1- Example 5 aminonaphthalene-7-sulfonic acid in 400 parts of water, the reaction being decidedly acid with 15.4 parts of 5-nitro-2-amino 1 hydroxyacetic acid. The coupling occupies 2-3 days. benzene are diazotized in usual manner and cou- The dyestuff formed is filtered and purified by reprecipitation from water.

pled in a solution alkaline with sodium bicarbonate with 24 parts of 2-amino-5-hydroxynaphthalene-7 -sulfonic acid. The resulting monoazo-dyestuff is filtered and washed with a per cent solution of sodium chloride for re-.

moving the excess of coupling component. The filter paste is dissolved in 1000 parts'of water by addition of 20 parts by volume of causticlsoda solution of 30 per cent strength at about 40 C. an aqueous solution of 6.9 parts of sodium nitrite is added and the whole is added to a mixture f ice and 46 parts by volume of hydrochloric acid of 30 per cent strength. while thoroughly I o 0 OH 0 OH 0 OH disazo-dyestufi separates by addition of sodium chloride and is filtered.

The filter paste is suspended in 2400 parts of water, the suspension heated to 60 C. and 135 parts by volume of caustic soda solution of 30 per cent strength as well as a solution of 8 parts of grape sugar in 80 parts of .water are added. The reaction mixture is stirred for about hour at 55-60 C., .100 parts of sodium chloride are added and after cooling the dyestuff is filtered and dried.

The dyestuff of the probable formula SOaH represents a blackish powder. solublein water and in dilute alkalis to blue s0lutions, in concentrated sulfuric acid to a reddish blue solution and dyeing cotton from a dye-bath containing sodium sulfate grey shades which become very fast when treated with copper sulfate.

Example '6 27.2 parts of 4:4-diaminodiphenyl-3:3-dicar boxylic acid are tetrazotized in usual manner and coupled with 14.5 parts of l-hydroxybenzene-2- carboxylic acid in a solution alkaline with sodium carbonate. After all of the tetrazo compound has disappeared there is added a solution of 25.6 parts of 2-amino-5-hydroxynaphthalene-7-sulfonic acid which has been neutralized with sodium carbonate, and coupling is effected at 1015 C. The resulting disazo-dyestufi is separated by adding sodium chloride and washed with a dilute solution'of sodium chloride.

This disazo-dyestuff is dissolved in 700 parts of water at 60'70 C., a solution of '7 .2 parts of sodium nitrite in 36 parts of water is added and after cooling to 05 C, the mixture is acidified by means of 80 parts by 'volume'of concentrated hydrochloric acid which has been diluted with an equal volume of water. Diazotization lasts about 12 to. 16 hours. This diazo-compound is coupled with 15 parts of 8-hydroxyquinoline in a solution alkaline with sodium carbonate. The trisazodyestufif is separated on addition of sodium chloride an'd,.iflnecessary, purified by dissolving in water and adding sodium chloride.

anddried.

This trisazo-dyestuff of the formula is a grey black powder soluble in water to a violet solution, in sodium carbonate solution of 10 percent strength to a reddish blue solution, in caustic soda solution of 10 per cent strength to a reddish violet solution-and in concentrated sulfuric acid to a-blue solution. It dyes cotton by the usual methodsof after-treating with copper salts in the dye-bath or in a fresh bath fast violet-blue shades.

HOaS

Example 7 18.4 parts of 4:4'-diaminodiphenyl are tetrazotized in usual manner and coupled with 14.5 parts of 1-hydroxybenzene-2-carboxylic acid in a solution alkaline with sodium carbonate at 610 concentrated hydrochloric acid.

C. After the tetrazo compound has disappeared there is added a solution of 26 parts of l-amino- 2-methoxynaphthalene-6-sulfonic acid, which has been neutralized with sodium carbonate, the

SOzH on on reaction mixture is .acidified with acetic acid and coupling is efiected at 1530 C. during. 16-20 hours. The disazo-dyestufi is filtered without addition of salt and washed with water.

The filter paste is suspended in 800 parts of Water and dissolved at '70-80 C. by addition of 10.6 partsoi anhydrous sodium carbonate. 7.2 parts of sodium nitrite are then added, the whole is cooled to 0-5". C. and acidified with a mixture of 30 parts of water and parts by volume of Diazotization lasts about-:12-l6 hours. Thediazo-compound is then coupled with 15 parts of 8-hydroxyquinoline at 10-15 C. in ;a solution alkaline with sodium carbonate. When coupling is finished, the reaction mixture is heated to C. and the dyestufi is separated by addition of sodium chloride.

When dry, the new trisazo-dyestuif represents a grey-black powder soluble in water to a brown- 1 011Ve solution, in sodium carbonate solution of 10 per cent strength and in caustic soda solution of 10 per cent strength to a brown solution, and in concentrated sulfuric acid to a blackish violet solution. .It corresponds to the formula OCHa } 1 0 OH N It is filtered is then coupled with 23.6 parts of'8-hydroxy- When treated with copper salts in the dye-bath or in a fresh bath it dyes cotton fast blackish brown shades.

Example 8 tion alkaline with sodiumcarbonate. When coupling'. is complete the dyestuff is precipitated by addition of sodium chloride."

When dry, the new 'trisazo-dyestuff of the 18.4 parts of 4:4'-diaminodiphenyl are tetrazo- 55 formula I COOH tized in usual manner and coupled with 4.5 1

without addition of salt and washed with water.

This dyestufi is dissolved in 800 parts of water and 10.6 parts of anhydrous sodium carbonate at '70-80 C., a solution of 7.2 parts of sodium nitrite in 36 parts of water is added and after coolin to 05 C. the mixture is acidified with a mixture of 50 parts by volume of concentrated hydrochloric acid and 50 parts of water. Diazotization lasts 16-20 hours. The diazo-compound is then coupled with 23.6 parts of.8-hydroxyquino line-"l-sulfonic acid at 10-15 C. in a solution alkaline with sodium carbonate; When coupling is complete the dyestufi is precipitated by addition of sodium chloride.

When dry, the new trisazo-dyestuft of the formula GOOH tion at l30 C. The disazo-dyestufi is filtered f I SOaH represents a grey-black powder soluble in water,

solution. When treated with copper salts. in the dye-bath or in a fresh bath it dyes cotton fast red-brown tints.

Example 9 18.4 parts of 4:4-diaminodiphenyl .are tetrazotized in usual manner and coupled with 14.5 parts of 1-hydroxy-benzene-2-carboxylic acid in a solution alkaline with sodium carbonate at 6- 10 C. As soon as the tetrazo solution has disappeared there is added a solution of 22;5'parts of 1 aminonaphthalene-Besulfonic acid neutralized with sodium carbonate and the reaction mass is acidified with acetic acid of 50 per cent strength. The coupling lasts about 16 hours at -30 C. The disazo-dyestuff is filtered without addition of salt and washed with water.

This dyestuff is dissolved in 800 parts of water and 10.6 parts of anhydrous sodium carbonate at IO-80 C., a sodium nitrite solution corresponding to 7.2 parts of NaNOz is added and after cooling to 05 C..the mixture is acidified with a mixture of 50 parts by volume of concentrated hydrochloric acid and 50 parts of water. Diazotization' lasts as a rule 16-20 hours. The diazo-compound quinoline-B-sulfonic acid at 10-15 C. in a solu- I S 03H Example 10 v 8.3 parts of the sodium salt of the dyestufi produced-according to Example 3 are dissolved in 500 parts of hot water, the solution is mixed with 2 parts of crystallized sodium acetate and after addition of parts of a copper sulfate solution of 10 per cent strength the Whole is SIOaH examples may be used. Instead of copper sulfate other copper salts as well as salts of other metals,

for instance cobalt or iron, may be used.

Errample 11 0 Into a dye-bath of 3000 parts of water containing 1.5 parts of the dyestuff obtainable as described in Example 3 as well as 2 parts of anhydrous sodium carbonate there are entered at C. 100 parts of cotton; the temperature is raised to 90 C. and there are added after hour 30 parts of crystallized sodium sulfate, whereupon the dyeing is continued for hour at 90-95 C. The goods are then rinsed and treated in a fresh bath containing 3 parts of crystallized copper sulfate and 1 part of acetic acid of 40 per cent strength at '7080 C. for hour. They are then rinsed as usual and if desired soaped for a short time and finished. The cotton is dyed fast grey-blue tints.

Example 12 within a hour, 30 parts of crystallized sodium sulfate are added and dyeing is continued for 1 hour at C. There is then added the solu-' tion which has been made from 1.5 parts of crystallized copper sulfate, 2.5 parts of tartaric acid,

'10Q parts of water and so much caustic soda solution that the solution reacts neutral. Dyeing is continued for hour at 90 C. and the goods are rinsed and dried as usual. Cotton, is dyed fast blue tints.

What we claim is: 1. Azo-dyestuffs built up from components selected from the group consisting of components of the benzene, naphthalene, triazine, dehydrothiotoluidine and carbazole series containing at least 3 azo-groups and at least one radical of a binuclear compound having the grouping typical for S-hydroxyquinoline.

2. Azo-dyestufi's built up from components selected from the group consisting of components of the benzene, naphthalene, triazine, dehydrothiotoluidine and carbazole series containing at least 3 azc-groups, further at least one salicylic acid grouping and finally at least one radical of a binuclear compound having the grouping typical for B-hydroxyquinoline.

3. Azo-dyestuffs of the general formula R1-N=N-Rz N=NRaN=NR4 Hooo wherein R1 stands for a benzene radical carrying the hydroxyl and carboxyl groups in ortho-position to each other, R2 and R3 stand for any aryl radicals and R4 stands for a radical of a binuclear j compound having the grouping ra V typical .for B-hydroziyqtflnoline.

CODE

4. Azo-dyestufi's of the general formula wherein R1 stands for a benzene radical carrying the hydroxyl and carboxyl groups in orthoposition to each other, Re stands for a diphenyl radical, R3 stands for a naphthalene radical and R4 stands for a radical of a binuclear compound having the grouping typical for B-hydroxyquinoline.

5. Azo-dyestuffs built up from components selected from the group consisting of components of the benzene, naphthalene, triazine, dehydrothiotoluidine and carbazole series containing at least 3 azo-groups and 2 radicals of a binuclear compound having the grouping H a g H wherein R1 stands for a benzene, radical, stands for a naphthalene radical and Rs stands 'for a radical of binuclear compound having the grouping typical for 8-hydroxyqulnoline.

7. The azo-dyestuff of the formula igngg figgm 8. The azo-dyestutfs of the formula I 1 0 0H N N=N SOaH HOaS H H H 9. The azo-dyestufis of the general formula N=NQOH N g typical for B-hydroxyquinoline.

11. Process for the manufacture of azo-dyestuffs containing at least 3 azo-groups, comprising unitingdiazo-azo-compounds containing at least 2 azo-groups and at least one salicylic acid radical built up from components selected from the group consisting of components of the benzene, naphthalene, triazine, dehydrothiotoluidine and carbazole series with binuclear compounds capable of coupling having the grouping typical for 8-hydroxyquinoline.

12. Process for the manufacture of trisazodyestuffs, comprising uniting compounds of the general formula wherein R1 is a benzene nucleus containing the hydroxyl and carboxyl groups in ortho-position to each other, R2 and R3 are aryl nuclei and D is a diazonium group, with binuclear compounds capable of coupling having the grouping I OH typical for 8-hydroxyquinoline.

13. Process for the manufacture of a trisazodyestufi, comprising uniting the diazo-compound of the formula HOQN=N N=N 1) wherein D is a diazonium group, with 8-hydroxyquinoline.

14. Process for the manufacture of a trisazodyestuff, comprising uniting the diazo-compound of the formula COOH HO D

wherein D is a diazonium group, with S-hydroxyquinoline.

15. Process for the manufacture of azo-dyestuffs containing at least 4 azo-groups, comprising reducing azo-dyestufis built up from components selected from the group consisting of components of the benzene, naphthalene, triazine, dehydrothiotoluidine and carbazole series containing at least 2 azo-groups and one nitrogroup and the radical of a binuclear compound having the grouping typical for 8-hydroxyquinoline, with reducing agents in such a manner that the nitro-group is converted into such a reduction stage which links two radicals of the dyestufi by a member of ahe group consisting of N=N- and 16. Process for the manufacture of azo-dyestuifs, comprising reducing disazo-dyestufis of the general formula wherein R1 is a benzene radical in which the nitroand azo-groups are in para-position to each other, R2 is a naphthalene radical and R3 is the radical of a compound having the groupi ll (:11 0 N typical for 8-hydroxyquinoline, with reducing agents in such a manner that the nitro-group is converted into such a reduction stage which links two radicals of the dyestufi' by a member of the group consisting of N=N and 17. Process for the manufacture of azo-dyestuffs, comprising reducing the azo-dyestuff of the formula S OaH with grape sugar in an alkaline medium.

FRITZ STRAUB. PETER PIETI-I. WALTER ANDERAU. WALTER HANHART. 

